An orientation is based on sexual attraction. Straights are straight because they desire the opposite sex, gays and lesbians are so because they feel sexual attraction to the same sex. Asexuals would form their own orientation the asexual orientation if asexuals actually didn't feel attraction, arousal or desire sex, much like atheists who have the absence of religious belief. Thus the current most common definition of an asexual is too unrealistic and does not really explain what is going on well on an individual or sociological basis, creates too much conflict and extra explaining, loose ends, caveats, etc.